Analyte detection in physiological fluids, e.g. blood or blood derived products, is of ever increasing importance to today's society. Analyte detection assays find use in a variety of applications, including clinical laboratory testing, home testing, etc., where the results of such testing play a prominent role in diagnosis and management in a variety of disease conditions. Analytes of interest include glucose for diabetes management, cholesterol, and the like. In response to this growing importance of analyte detection, a variety of analyte detection protocols and devices for both clinical and home use have been developed. Some of these devices include electrochemical cells, electrochemical sensors, hemoglobin sensors, antioxidant sensors, biosensors, and immunosensors.
One characteristic of blood that can affect analyte detection is the hematocrit. Levels of hematocrit can be vastly different amongst various people. By way of non-limiting example, a person suffering from anemia may have a hematocrit level of approximately 20% while a neonate may have a hematocrit level of approximately 65%. Even samples taken from the same individual over a period of time can have different hematocrit levels. Further, because high hematocrit can also increase the viscosity of blood, and viscosity can in turn affect other parameters associated with analyte detection, accounting for the effect of hematocrit on a sample can be important in making accurate analyte concentration determinations.
One way in which varying levels of hematocrit in a blood sample have been accounted for is by separating the plasma from the blood and then recalculating the concentration of the antigen with respect to the adjusted plasma volume. Separation has been achieved, for example, by performing a centrifugation step. Other ways in which the varying levels of hematocrit in a blood sample have been accounted for include using an average hematocrit in a calculation or measuring a hematocrit in a separate step and then calculating the concentration of the antigen with respect to the plasma value. These methods, however, are believed to be undesirable, at least because they involve unwanted sample handling, take additional time, and lead to substantial errors in the final determinations. Further, temperatures in environments where samples are analyzed can also have a negative impact on the accuracy of analyte concentration determination.
Accordingly, it would be desirable to develop a way to obtain more accurate analyte concentration measurements that account for a wide spectrum of hematocrit levels and temperatures. It would also be desirable to develop a way to determine hematocrit levels quickly.